ST. LOUIS (KSDK) - One day after the U.S. Senate rejected a bill that would have expanded background checks on guns, one of St. Louis' most powerful and staunch supporters of gun rights ended his lifetime membership with the National Rifle Association (NRA).

In an email sent exclusively to NewsChannel 5's Leisa Zigman, Adolphus Busch IV, an heir to the Busch family fortune, asked the gun rights group to "immediately" remove his name from its membership roles.

An avid environmentalist and hunter, guns have been a part of Busch's life since he was a child.

"It's something you never forget being able to be in the outdoors with your father," Busch said in a 2005 interview with KSDK.

Busch, whose great-grandfather founded Anheuser-Busch, made clear his position on guns and the people who legally use them.

"Hunters put back everything they take out and more," he said at the time.

Now, the man who joined the NRA in 1975 is cutting ties.

In a letter addressed to NRA President David Keene, Busch writes, "It disturbs me greatly to see this rigid new direction of the NRA."

"...One only has to ask why the NRA reversed its original position on background checks. Was it not the NRA position to support background checks when Mr. LaPierre himself stated in 1999 that NRA saw checks as 'reasonable'?"

"...I fail to see how the NRA can disregard the overwhelming will of its members who see background checks as reasonable," Busch writes.

On its website, the NRA fiercely opposed the Senate background check legislation, calling the amendment "misguided." It's clear from Busch's email he does not agree.

"I am simply unable to comprehend how assault weapons and large capacity magazines have a role in your vision," he said. "The NRA I see today has undermined the values upon which it was established. Your current strategic focus clearly places priority on the needs of gun and ammunition manufacturers while disregarding the opinions of your 4 million individual members."

"One only has to look at the makeup of the 75-member board of directors, dominated by manufacturing interests, to confirm my point. The NRA appears to have evolved into the lobby for gun and ammunition manufacturers rather than gun owners."

NewsChannel 5 attempted to get comment from David Keene regarding Busch's letter, but we were told that he has yet to receive the letter and will not comment until he reads it.